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[4]: 114 A DataFrame is a 2-dimensional data structure of rows and columns, similar to a spreadsheet, and analogous to a Python dictionary mapping column names (keys) to Series (values), with each Series sharing an index. [4]: 115 DataFrames can be concatenated together or "merged" on columns or indices in a manner similar to joins in SQL.
The pandas package in Python implements this operation as "melt" function which converts a wide table to a narrow one. The process of converting a narrow table to wide table is generally referred to as "pivoting" in the context of data transformations.
Layers were introduced in Western markets by Fauve Matisse (later Macromedia xRes), [2] [better source needed] and then available in Adobe Photoshop 3.0, in 1994, which lead to wide-spread adoption. In vector image editors that support animation, layers are used to further enable manipulation along a common timeline for the animation; in SVG ...
Length Both Yes Yes Explicit Explicit DPI (PPI) for rasterized images, fonts or effects PNG: Pixel Raster No Implicit when density is set Optional PPM, 4 bytes each horizontal and vertical directions [27] PPM: Pixel Raster Yes No No No PSD and PSB: Length or pixel Both No Explicit for length. No for pixel Optional SVG: Length or pixel Both Yes No
The crop factor is sometimes referred to as the focal length multiplier ("Film") since multiplying a lens focal length by the crop factor gives the focal length of a lens that would yield the same field of view if used on the reference format. For example, a lens with a 50 mm focal length on an imaging area with a crop factor of 1.6 with ...
35 mm equivalent focal lengths are calculated by multiplying the actual focal length of the lens by the crop factor of the sensor. Typical crop factors are 1.26× – 1.29× for Canon (1.35× for Sigma "H") APS-H format, 1.5× for Nikon APS-C ("DX") format (also used by Sony, Pentax, Fuji, Samsung and others), 1.6× for Canon APS-C format, 2× for Micro Four Thirds format, 2.7× for 1-inch ...
An interesting property of the upper box dimension not shared with either the lower box dimension or the Hausdorff dimension is the connection to set addition. If A and B are two sets in a Euclidean space, then A + B is formed by taking all the pairs of points a , b where a is from A and b is from B and adding a + b .
The 1961 35 mm f / 3.5 PC-Nikkor lens—the first perspective-control lens for a 35 mm camera. In photography, a perspective-control lens allows the photographer to control the appearance of perspective in the image; the lens can be moved parallel to the film or sensor, providing the equivalent of corresponding view camera movements.